The present invention relates to systems for interfacing a host computer to a high speed Local Area Network (LAN). More particularly, it relates to bus interface units for interfacing a host computer having a parallel bit output to a data bus carrying a plurality of messages serially. The bus interface unit is part of the apparatus called a port which is the device connecting the bus and a host computer.
The connection of a number of host computers to a data bus presents no special difficulties if speed of transmission is not of great importance. Appropriate signals may be placed on to the bus so that collisions between messages do not occur. Further, if immediate processing is not essential, error checking of the information on the bus is performed by having a subsequent message instruct a receiver to ignore a prior message, or by conducting an error checking routine after a full message has been stored in a buffer but before it is transmitted. However, such approaches are not suitable for the transmission of data at extremely high rates and in real time applications such as aircraft systems, where the information transmitted on the bus must be acted upon promptly and processing delays are not acceptable.